Ketone derivatives, reduction

Reductive amination of methyl ketoreserpate was studied in detail. The use of re-propylamine in the presence of a palladium-charcoal catalyst led not only to the expected mixture of a- and /3-amino derivatives (X), but also to a methyl 17-demethoxy-18-deoxy-l 8-re-propyl -aminoreserpate (XII). In the last case, no attempt was made to define the stereochemistry at C-16 and C-18. Similar eliminations of the C-17 methoxyl under basic conditions were also encountered with other ketone derivative. Reductive aminations were also effected with secondary amines. Piperidine yielded as the sole insolable product the... 

A large variety of methods is applicable to the formation of isolated double bonds. This permits selection of reagents compatible with other functionality present. Alcohol dehydration, ester elimination and other nonreductive p eliminations are the most common methods. Reductive elimination of halo-hydrins, vic-dihalides, etc., and of a variety of ketone derivatives has also been used. 

Garcia et al. has extended the Batcho-Leimgruber procedure to the synthesis of 2-substituted indoles. Treatment of 36 with o-fluorobenzoyl chloride 37, followed by in situ hydrolysis and deformylation gave ketone 38. Reduction of nitroarylketone 38 with sodium hydrosulfite then furnished indole 39. Similarly, bromoacetylation of 36 gave an acylenamine which was converted into the phthalimido derivative 40. Hydrolysis and deformylation gave phthalimidoketone 41 which underwent reductive cyclization to furnish indole 42. 

Aldehydes and ketones of furazans and furoxans have many properties resembling those of the aryl derivatives. Reduction of the carbonyl compounds with... 

The first synthesis of stable 3-hydroperoxy-sultams (24) which are a new class of sultam with oxidising properties, was reported. The synthesis involved oxidation of the isothiazolium salts (23) with hydrogen peroxide in acetic acid. Reduction of (24) with aqueous sodium bisulphite afforded the corresponding novel 3-hydroxysultams whereas thermolysis in ethanol resulted in the elimination of water to give 3-ketone derivatives, which are versatile as dieneophiles <96T783>. 

Halocarbons, ketone-alcohol reduction, 84 Halogenation, 4-methylbenzyl chloride [reductive halogenation of aldehyde to benzyl chloride], 124 Hemiacetals, reduction of, 97-99 Hemiaminals, reduction of, 99-100 Hemiketals, reduction of, 97-99 Heptene derivatives, alkene to alkane reductions, disubstituted alkenes, 36-38... 

Types of compounds are arranged according to the following system hydrocarbons and basic heterocycles hydroxy compounds and their ethers mercapto compounds, sulfides, disulfides, sulfoxides and sulfones, sulfenic, sulfinic and sulfonic acids and their derivatives amines, hydroxylamines, hydrazines, hydrazo and azo compounds carbonyl compounds and their functional derivatives carboxylic acids and their functional derivatives and organometallics. In each chapter, halogen, nitroso, nitro, diazo and azido compounds follow the parent compounds as their substitution derivatives. More detail is indicated in the table of contents. In polyfunctional derivatives reduction of a particular function is mentioned in the place of the highest functionality. Reduction of acrylic acid, for example, is described in the chapter on acids rather than functionalized ethylene, and reduction of ethyl acetoacetate is discussed in the chapter on esters rather than in the chapter on ketones. 

Propyleine (104) also is derivable from ketone 437. Reduction of 437 with LAH gave the equatorial alcohol (438) which was converted into the corresponding mesylate (439). Clean elimination was effected by heating 439 with potassium carbonate in dimethylsulfoxide to yield a 3 1 mixture of propyleine (104) and isopropyleine (440) (Scheme 54) 455). 

The most conspicuous property of aliphatic amines, apart from their fishy smell, is their high basicity, which usually precludes N-alkylations under acidic reaction conditions (last reaction, Scheme 6.3). Hence, alkylation of amines with tertiary alkyl groups is not usually possible without the use of highly stabilized carbocations which can be formed under basic reaction conditions. Rare exceptions are N-alkyla-tions of amines via radicals (Scheme 4.2), copper-catalyzed propargylations (Scheme 6.3), and the addition of amines to some Michael acceptors and allyl palladium or iridium complexes. Better strategies for the preparation of tert-alkylamines include the addition of Grignard reagents to ketone-derived imines [13] or the reduction of tert-alkyl nitro compounds. 

In the manufacture of hexylresorcinol, resorcinol and caproic acid are heated with a condensing agent, such as zinc chloride, and the intermediate ketone derivative is formed, which is purified by vacuum distillation. After reduction with zinc amalgam and hydrochloric acid, impure hexylresorcinol is formed, which can be purified by vacuum distillation. 

Analogous with the previous results of enol silyl ethers of ketones, nonsubstituted ketene silyl acetals are found to exhibit lower levels of stereoregulation, while the propionate-derived ketene silyl acetals display a high level of asymmetric induction. The reactions with aliphatic aldehydes, however, resulted in a slight reduction in optical and chemical yields. With phenyl ester-derived ketene silyl acetals, syn adducts predominate, but the selectivities are moderate in most cases in comparison with the reactions of ketone-derived silyl enol ethers. Exceptions are a,p-unsaturated aldehydes, which revealed excellent diastereo- and enantioselectivities. The observed syn selectivity and re-face attack of nucleophiles on the carbonyl carbon of aldehydes are consistent with the aforementioned aldol reactions of ketone-derived enol silyl ethers. 

Enantioselective Reduction of a,p-Enones. Oxazaborolidine catalyst Ic was also found to be a superior catalyst compared to la and lb for the reducdon of a,p-unsaturated ketone derivatives (eq 5). It is interesdng to note that the presence of a bulky substituent at the p-posidon is mandatory for high enandocon-trol. This reaction has been used as a key step in the synthesis of atractyligenin. This catalyst has also been used to reduce a,p-unsaturated ketones bearing a trifluoromethyl group in 87% ee. ... 

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